Butene copolymerization

Dependence on Metallocene Symmetry of E-Z Selectivity for 2-Butene Copolymerizations. We have seen in the Section 3.1.3 that opposite enantiofaces are favored for primary and secondary propene insertion on C2-symmetric metallocenes, whereas the same enantioface is favored for primary and secondary insertion on Cv-symmetric metallocenes. In this framework, if the same steric interactions which rule the enantioselectivity of primary and secondary propene insertions hold for 2-butene, the insertion of... 

To investigate this idea, which would confirm and summarize a large class of widely accepted mechanisms, the insertion reactions of (Z)- and (E)-butene with catalytic systems based on the C2-symmetric Me2Si(l-Ind)2 ligand and on the ((-symmetric Me2Si(Cp)(9-Flu) ligand have been recently studied. A double approach based on combined quantum mechanics/molecular mechanics (QM/MM) techniques and on selected ethene/2-butene copolymerization runs has recently been utilized.94... 

As for olefins different from propene, molecular modeling studies have also been able to rationalize the dependence on metallocene symmetry of E-Z selectivity for 2-butene copolymerization as well as the stereoselectivity of the cyclization step, which determines the cis or trans configuration of the rings, for cyclopolymerization of nonconjugated dienes. 

With the second approach to the preparation of the catalytic system, only methylenebis(dichloroaluminium) was prepared by an electrolytic reaction31. In the flow sheet proposed in the patent, between the electrolytic cell and the polymerization vessel a mixing reactor is interposed, where the various transition metal derivatives are added to the aluminium containing solution. Following this method other monomers, such as butadiene, 1-butene (copolymerized with ethylene), and vinyl chloride were successfully polymerized. 

The stereochemical features of the polymerization were satisfactorily accounted for by considering the nonbonded interactions between the monomer molecule undergoing insertion and the ligands on the vanadium atom. Coordination number five for vanadium was chosen to justify the more relevant data concerning the propylene polymerization and ethylene, 1-butene, and cis-2-butene copolymerization. 

These predictions were confirmed by ethene/2-butene copolymerizations. In fact, C2-symmetric metallocenes scarcely insert, less than 2%, Z-butene, while they insert relevant fractions, 25%, of Z-butene analogously, Cs-symmetric metallocenes insert less than 2% of Z-butene, while inserting 14% of Z-butene. ... 

Borstar is an industrial olefin polymerization plant/technology, which combines different polymerization processes and reactor units, utilizing an advanced catalytic system. In the present work, a detailed model for the dynamic and steady-state simulation of this industrial plant has been developed. A comprehensive kinetic model for the ethylene-1-butene copolymerization over a two-site catalyst was employed to predict the MWD and CCD in the Borstar process. The Sanchez-Lacombe equation of state (S-L EoS) was employed for the thermodynamic properties of the polymerization system and the phase equilibrium calculations in the process units. 

In this work a mesoscale/macroscale level approach of the Borstar plant is attempted focusing on the study of average polymer properties, dynamic behaviour and control of process units. To describe the kinetic of ethylene-1-butene copolymerization in the plant a unified kinetic scheme for the three reactor units based on a two-site Ziegler catalyst is employed (Table 1). The symbol denotes the concentration of live copolymer chains of total length n ending in an i monomer unit, formed at the k catalyst active site. Pp and denote the concentrations of the activated vacant catalyst sites of... 

This patent describes the reaction product obtained from the treatment of magnesium alcoholates such as Mg(OEt)2 with tetravalent titanium compounds such as TiC OR) or TiCl. Ethylene homopolymerizations and ethylene/1-butene copolymerizations were investigated and the polyethylene produced possessed a narrow molecular weight distribution as indicated from M /M values of 2-4 measured on the polyethylene samples. The polyethylene was described as especially suitable for the production of injection-molded articles. Catalyst Preparation 11 g of MgjOEt) was suspended in 50 ml of Diesel oil (boiling range of 130-160°C) and 200 ml of a 1 molar... 

Table 7. Typical productivities In kg/g cat. In gas phase ethylene-butene copolymerization.

Table 8. Gas phase ethylene-butene copolymerization at 85 C. Effect of the catalyst and butene content on melt index and melt flow ratio ( 21. / 2.16) different comonomer content given by the number of ethyl branches. PTES, dpdms and DBF are respectively for phenyltrlethoxysllane, dlphenyl-dlmethoxysllane, dibutylphtalate.

G-5—G-9 Aromatic Modified Aliphatic Petroleum Resins. Compatibihty with base polymers is an essential aspect of hydrocarbon resins in whatever appHcation they are used. As an example, piperylene—2-methyl-2-butene based resins are substantially inadequate in enhancing the tack of 1,3-butadiene—styrene based random and block copolymers in pressure sensitive adhesive appHcations. The copolymerization of a-methylstyrene with piperylenes effectively enhances the tack properties of styrene—butadiene copolymers and styrene—isoprene copolymers in adhesive appHcations (40,41). Introduction of aromaticity into hydrocarbon resins serves to increase the solubiHty parameter of resins, resulting in improved compatibiHty with base polymers. However, the nature of the aromatic monomer also serves as a handle for molecular weight and softening point control. 

Polymers account for about 3—4% of the total butylene consumption and about 30% of nonfuels use. Homopolymerization of butylene isomers is relatively unimportant commercially. Only stereoregular poly(l-butene) [9003-29-6] and a small volume of polyisobutylene [25038-49-7] are produced in this manner. High molecular weight polyisobutylenes have found limited use because they cannot be vulcanized. To overcome this deficiency a butyl mbber copolymer of isobutylene with isoprene has been developed. Low molecular weight viscous Hquid polymers of isobutylene are not manufactured because of the high price of purified isobutylene. Copolymerization from relatively inexpensive refinery butane—butylene fractions containing all the butylene isomers yields a range of viscous polymers that satisfy most commercial needs (see Olefin polymers Elastomers, synthetic-butylrubber). 

Dicbloro-l,3-butadiene [1653-19-6] is a favored comonomer to decrease the regularity and crystallization of chloroprene polymers. It is one of the few monomers that will copolymerize with chloroprene at a satisfactory rate without severe inhibition. It is prepared from by-products or related intermediates. It is also prepared in several steps from chloroprene beginning with hydrochlorination. Subsequent chlorination to 2,3,4-trichloto-1-butene, followed by dehydrochlorination leads to the desired monomer in good yield if polymerization is prevented. 

Polybutenes. Copolymerization of mixed isobutylene and 1-butene containing streams with a Lewis acid catalyst system yields low mol wt (several hundred to a few thousand) copolymers that are clear, colorless, viscous Hquids. The chain-ends are unsaturated, and they are often chemically modified through this functionaUty (7,73). 

Novel polyethylene materials have been synthesized by copolymerization of ethylene with 1-butene, 1-hexene, and/or 1-octene using metallocene catalyst systems [9]. 

Copolymerization e.g., of 1-butene or 1-hexene with ethylene, gives short-chain branching-, e.g., the branches contain three or five carbon atoms. The random location of the side-chains lowers the crystallinity and density. Long-chain branching refers to branches that are similar in length to the polymer backbone and this type occurs in polyethylene manufactured using the... 

It has been shown by Barb and by Dainton and Ivin that a 1 1 complex formed from the unsaturated monomer (n-butene or styrene) and sulfur dioxide, and not the latter alone, figures as the comonomer reactant in vinyl monomer-sulfur dioxide polymerizations. Thus the copolymer composition may be interpreted by assuming that this complex copolymerizes with the olefin, or unsaturated monomer. The copolymerization of ethylene and carbon monoxide may similarly involve a 1 1 complex (Barb, 1953). 

The sterically unencumbered catalyst active site allows the copolymerization of a wide variety of olefins with ethylene. Conventional heterogeneous Ziegler/Natta catalysts as well as most metallocene catalysts are much more reactive to ethylene than higher olefins. With constrained geometry catalysts, a-olefins such as propylene, butene, hexene, and octene are readily incorporated in large amounts. The kinetic reactivity ratio, rl, is approximately... 

The monomers used to make an addition polymer need not be identical. When two or more different monomers are polymerized into the same chain, the product is a copolymer. For instance, we routinely copolymerize ethylene with small percentages of other monomers such as a-olefins (e.g., 1-butene and 1-hexene) and vinyl acetate. We call the products of these reactions linear low density polyethylenes and ethylene-vinyl acetate copolymer, respectively. We encounter these copolymers in such diverse applications as cling film, food storage containers, natural gas distribution pipes, and shoe insoles. 

We can incorporate short chain branches into polymers by copolymerizing two or more comonomers. When we apply this method to addition copolymers, the branch is derived from a monomer that contains a terminal vinyl group that can be incorporated into the growing chain. The most common family of this type is the linear low density polyethylenes, which incorporate 1-butene, 1-hexene, or 1-octene to yield ethyl, butyl, or hexyl branches, respectively. Other common examples include ethylene-vinyl acetate and ethylene-acrylic acid copolymers. Figure 5.10 shows examples of these branches. 

The ethylene-1-butene block cannot be obtained directly since the two monomers do not undergo anionic copolymerization. 

Certain half-sandwich phenoxides have been shown to be highly active olefin polymerization catalysts. For example, the zirconium complex (60) polymerizes ethylene with an activity of 1,220 gmmol-1 h-1 bar-1.181 A similar titanium complex (61) displays an activity of 560gmmol ll bar 1 at 60°C.182-189 Comparable activities were also recorded for the copolymerization of ethylene with 1-butene and 1-hexene. 

In agreement with the theoretical analysis, C2- and /(-symmetric metallocenes scarcely insert ( > and (Z)-butene, respectively, whereas C2- and Cs-symmetric metallocenes insert relevant fractions of (Z)- and (//(-butene, respectively. Moreover, in agreement with QM/MM analysis, when copolymerization experiments are run with a 40% (Z)-2-butene-60% ( )-2-butene mixture, the presence of the better coordinating (Z)-butene inhibits the reaction... 

In summary, the prediction that (E)-(Z) selectivity in the ethene/intemal olefins copolymerization with group 4 metallocenes can be achieved by using ligands of suitable symmetry has been proved. In particular, it has been shown that C2- and Os-symmetric metallocenes are able to copolymerize ethene with (Z)- and ( >butene, respectively. 

Ethylene-1-butene copolymers, 20 180 Ethylene-1-olefin copolymerization, 26 525 Ethylene-acrylic elastomers, 10 696-703 commercial forms of, 10 697-698 dynamic mechanical properties of,... 

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